1. Field of the Invention
This invention relates to lamps utilizing light bulbs. More particularly, this invention relates to lamps for surgery having convection-induced ventilation for cooling.
2. Related Art
Many surgical lighting fixtures have been developed to provide high intensity light having a high color temperature that reduce the heat radiated toward the patient. Excess heat dries tissues during surgery. Color temperatures less than about 3,500.degree. K. distort colors that a surgeon frequently relies on to diagnose disease and the patient's condition, making color-corrected lighting important.
One effort to develop such a lamp is disclosed in U.S. Pat. No. 4,032,771, issued to Ilzig on June 28, 1977, which discloses a surgical operating lamp with mainly cold light radiation which results from the reflection of the infrared portion of the light spectrum emanating from a light source through a concave cold light reflector that reflects the infrared toward a heat absorbing body surrounding the lamp body. An outer bell surrounds the heat absorbing body and the passageway formed between the outer bell and the heat absorbing body conducts the heated air to a vent outlet, thereby cooling the lamp.
Another such development is disclosed in U.S. Pat. No. 3,588,488 issued to Lauterbach on June 28, 1971, which discloses a surgical light fixture having a high Kelvin rating of approximately 6,000.degree. K., which is attained by raising the color temperature of the illumination source from 3,000.degree. K. to 6,000.degree. K. This increase is attained by employing an internal cylindrical filter and a dichroic reflector surrounding the internal filter.
The systems such as those disclosed in the Ilzig and the Lauterbach patents are expensive to manufacture. They are, in fact, too expensive for many potential applications such as animal surgery.
Accordingly, there is a need for a relatively inexpensive color corrected surgery light that provides high intensity shadow-free illumination for use by veterinarians or others during surgery.